Using bsdinstall for an additional drive

[Doug Hardie]

I have a running 9.2 system that I need to add another drive to.  With sysinstall it was easy (once you understood it) to add a new drive.  However, I have not figured out how to do that with bsdinstall.  I don't want to experiment much as the running system would take forever to rebuild.  Is there a way to do this without affecting the existing system?